lib: add option to start/stop wheel timer

This fix add option to start and stop a wheel timer

Signed-off-by: Soumya Roy <souroy@nvidia.com>

Author: soumyar-roy

lib/wheel.c

@@ -17,12 +17,14 @@ DEFINE_MTYPE_STATIC(LIB, TIMER_WHEEL_LIST, "Timer Wheel Slot List");
 static int debug_timer_wheel = 0;
 
 static void wheel_timer_thread(struct event *t);
+static void wheel_pause(struct timer_wheel *wheel);
+static void wheel_start(struct timer_wheel *wheel);
 
 static void wheel_timer_thread(struct event *t)
 {
 	struct listnode *node, *nextnode;
 	unsigned long long curr_slot;
-	unsigned int slots_to_skip = 1;
+	int slots_to_skip = 1;
 	struct timer_wheel *wheel;
 	void *data;
 
@@ -47,6 +49,16 @@ static void wheel_timer_thread(struct event *t)
 		slots_to_skip++;
 
 	wheel->slots_to_skip = slots_to_skip;
+	if ((((curr_slot + slots_to_skip) % wheel->slots) == curr_slot) &&
+	    list_isempty(wheel->wheel_slot_lists[curr_slot])) {
+		/* Cam to back to same slot and that is empty
+		 * so the wheel is empty, puase it
+		*/
+		wheel_pause(wheel);
+		zlog_debug("Pasued an empty  wheel %p", wheel);
+		return;
+	}
+
 	event_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
 			     wheel->nexttime * slots_to_skip, &wheel->timer);
 }
@@ -63,7 +75,6 @@ struct timer_wheel *wheel_init(struct event_loop *master, int period,
 
 	wheel->slot_key = slot_key;
 	wheel->slot_run = slot_run;
-
 	wheel->period = period;
 	wheel->slots = slots;
 	wheel->curr_slot = 0;
@@ -75,9 +86,6 @@ struct timer_wheel *wheel_init(struct event_loop *master, int period,
 	for (i = 0; i < slots; i++)
 		wheel->wheel_slot_lists[i] = list_new();
 
-	event_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
-			     wheel->nexttime, &wheel->timer);
-
 	return wheel;
 }
 
@@ -104,7 +112,7 @@ int wheel_add_item(struct timer_wheel *wheel, void *item)
 		zlog_debug("%s: Inserting %p: %lld %lld", __func__, item, slot,
 			   slot % wheel->slots);
 	listnode_add(wheel->wheel_slot_lists[slot % wheel->slots], item);
-
+	wheel_start(wheel);
 	return 0;
 }
 
@@ -121,3 +129,15 @@ int wheel_remove_item(struct timer_wheel *wheel, void *item)
 
 	return 0;
 }
+
+static void wheel_pause(struct timer_wheel *wheel)
+{
+	EVENT_OFF(wheel->timer);
+}
+
+static void wheel_start(struct timer_wheel *wheel)
+{
+	if (!event_is_scheduled(wheel->timer))
+		event_add_timer_msec(wheel->master, wheel_timer_thread, wheel, wheel->nexttime,
+				     &wheel->timer);
+}

lib/wheel.h

@@ -17,7 +17,7 @@ struct timer_wheel {
 	long long curr_slot;
 	unsigned int period;
 	unsigned int nexttime;
-	unsigned int slots_to_skip;
+	int slots_to_skip;
 
 	struct list **wheel_slot_lists;
 	struct event *timer;